Fuel metering control system and cylinder air flow estimation method in internal combustion engine

摘要

Fuel metering control system in an internal combustion engine utilizing adaptive control having an intake manifold wall's fuel adherence plant. In the system, an actual air/fuel ratio in the individual cylinders is accurately estimated using an exhaust manifold model with an observer. Also, an actual cylinder air flow is estimated using a fluid model. Based on them, a desired cylinder fuel flow is determined by dividing the actual cylinder air flow by a desired air/fuel ratio and an actual cylinder fuel flow is determined by dividing the actual cylinder air flow by the estimated actual air/fuel ratio. The adaptive controller operates such that the actual cylinder fuel flow constantly coincides with the desired cylinder fuel flow. In an embodiment, in order to respond the change in wall adherence parameters, a compensator is connected in series with the wall adherence plant, a virtual plant incorporating the compensator is postulated and when the transfer characteristics of the virtual plant is other than 1 or thereabout, the adaptive controller is operated to have a transfer characteristics inverse thereto. At the same time, a method for estimating cylinder air flow inducted in the engine using the aforesaid fluid model is explained.